1. Field of the Invention
The present invention relates to a process for producing a preformed wire from silicon carbide fiber-reinforced aluminum as an intermediate material of FRM, and particularly to a process for producing a preformed wire of the kind as described above which is prevented from deteriorating in strength at high temperatures. The concept of a preformed wire as defined in the present invention comprehends preformed sheet and tape as well.
2. Prior Art
Composite materials composed of a metal, such as aluminum, and a fibrous material, such as a silicon carbide fiber, impregnated therewith have heretofore been promising and expected as materials widely applicable to vehicles, airplanes, rockets, spacecraft, and the like by virtue of their merits respectively attributable to the metal and the fibrous material, such as toughness, lightness, and flexibility.
Various methods of producing such a metal-fiber composite material have been proposed. One example of them is a method comprising blowing fine metallic particles or a metallic vapor against a bundle of fibers by plasma jetting, metallikon, or vacuum evaporation to adhere a metal to the surfaces of the fibers to thereby produce a metal-fiber composite material or precursor thereof. However, this method is defective in that no composite material having satisfactory strength and elasticity can be obtained because fine metallic particles or a metallic vapor is so straight forward blown against a bundle of fibers that the metal cannot penetrate well into the inside of the fiber bundle.
Another proposed method comprises dipping a bundle of fibers in a molten metal bath while ultrasonically vibrating the molten metal bath to cause the molten metal to penetrate into the inside of the fiber bundle. In this case, although a bundle of fibers is opened by ultrasonic vibration to expel air present inside the fiber bundle so that the metal is allowed to penetrate well into the inside of the fiber bundle, the fibers are fixed in a disorderly opened state due to the vibration so that a difficulty is encountered in imparting desired strength and elasticity to the resulting metal-fiber composite material.
A method disclosed in Japanese Patent Laid-Open No. 34,167/1986 was proposed with a view to solving the above-mentioned problems. This method comprises spreading and arranging in order a bundle of silicon carbide fibers, and passing the bundle of silicon carbide fibers through a melt of a metal such as aluminum while ultrasonically vibrating the melt. However, this method is insufficient to prevent deterioration in strength of the resulting composite material at high temperatures. Namely, in the production of a preformed wire from silicon carbide fiber-reinforced aluminum when fibers are impregnated with an aluminum melt at a high temperature for a long period of time, an interfacial reaction occurs in the surface layers of the fibers to deteriorate the same. Some improvement can be attained against the deterioration of fibers when the melt is ultrasonically vibrated to shorten the time of impregnation for the purpose of preventing the deterioration. However, the improvement is yet insufficient. Moreover, the strength characteristics of the resulting composite material at high temperatures cannot be improved.
The present invention has been made in view of the above-mentioned state of art. An object of the present invention is to provide a process for producing a preformed wire from silicon carbide fiber-reinforced aluminum which is prevented from deteriorating in strength at high temperatures by causing aluminum to penetrate well in between the fibers at a low temperature to effect impregnation without deterioration of the fibers.